This invention relates generally to integrated gasification combined-cycle (IGCC) power generation systems, and more particularly to methods and systems for reducing cooling water and power consumption in gasification systems.
At least some known IGCC systems include at least one power producing gas and/or steam turbine system that is integrated with a gasification system such as, but not limited to, a carbon-to-liquids gasification system. Such known carbon-to-liquids gasification systems may include a coal-to-liquids (CTL) gasification system. At least some known CTL gasification systems include an air separation unit, a gasifier, and a Fisher-Tropsch (F-T) synthesis reaction system.
Known air separation units may include an integrated air compressor such as, but not limited to, a multi-stage air compressor including a plurality of stages. Known multi-stage air compressors typically include a series of cooling water exchangers that are disposed between adjacent compressor stages to provide inter-cooling to the compressed air and to remove heat generated as the air is compressed. To reduce the overall temperature of the compressed air to a desired temperature, such as a close-to-ambient temperature, a larger cooling water duty than is typically available may be required. As such, some known gasification systems may not be optimal for water-constrained sites.
Known gasifiers and F-T synthesis reaction systems generally produce a significant amount of by-product steam generated through reactions occurring within the systems. Although most of the steam produced is low-pressure steam, the steam may be channeled through a steam condensing cycle that includes a condenser to transform water vapor into a liquid condensate, which may be used, for example, as boiler feedwater. However, to remove a substantial amount of heat, known condensers may require a larger cooling water duty than is available. As such, at least some known gasification systems may not be optimal for water-constrained sites.